This invention relates to a method of manufacturing an organic thin-film EL (Electroluminescent) device in which a plurality of thin-film luminescent portions formed by organic EL luminescent material or electrode material on a substrate surface are arranged to a matrix shape with fine pitches.
In particular, this invention relates to a method of manufacturing the organic thin-film EL device for forming the luminescent portions with a pattern mask by using vacuum vaporizing method.
In an organic thin-film EL (Electroluminescent) device, holes are injected from an anode into a luminescent layer while electrons are injected from a cathode into the luminescent layer.
Under this circumstance, the holes and the electrons recombine in the luminescent layer, and emit a light beam via an excitation state.
In this case, examination has been made about a variety device structures in accordance with nature of luminescent material of the luminescent layer with respect to the organic thin-film layer.
Basically, the device is structured by sandwiching the organic luminescent layer, which emits a strong fluorescent light beam, between the anode and the cathode.
Further, it is effective to arrange a charge injecting and transporting layer, such as, a hole injecting and transporting layer and an electron injecting and transporting layer or to dope guest molecule into the organic luminescent layer in order to achieve high luminescent efficiency and stable drive.
Moreover, another examination has been made about electrode material in particular, the cathode material to enhance the luminescent efficiency and lifetime characteristic.
Meanwhile, performance for a practical use has been realized by improving a device structure or device material, although not sufficient.
Recently, report has been made about a prototype of an organic thin-film EL display having multi-color as application of the organic thin-film EL device.
Still another examination has been made about a variety of methods as the color system of the organic thin-film EL display having multi-color. The color system includes a system (three color independent luminescent system) in which luminescent devices having the respective colors are arranged on a substrate in parallel, a system (CCM system) in which a color conversion layer is provided in a light taking-out plane using blue luminescent as an EL luminescent source, and a system (color filter system) in which white luminescent is used as an EL luminescent source and full-color display is carried out using a color filter.
In this event, the three-color independent luminescent system is superior from the viewpoint of effectively utilizing luminescent efficiency with a simple structure.
Another report has been made about the color organic thin-film EL display, which has 5.7 inch at diagonal and pixels of 320.times.240, as a prototype of the color organic thin-film EL display utilizing the color independent luminescent system, in NEC Technical Journal, vol. 51, No.10, pp. 28-32 (1998).
In this event, pixel size of the display is equal to 0.36 mm.times.0.36 mm while sub-pixel pitch of the luminescent layer (namely, the luminescent portion) is equal to 0.12 mm (120 .mu.m). Herein, it is to be noted that the pitch of the sub-pixel means a distance from an edge of one luminescent portion to an edge of the adjacent luminescent portion.
Similarly, still another report has been made about a full-color organic thin-film EL display, which has 5.7 inch at diagonal and pixels of 320.times.240 in Extended Abstracts of 9-th International Workshop on Inorganic and Organic Electro-luminescence, September 14-17, pp. 137-140 (1998).
In this case, trio-pitch of the luminescent portion of the display is equal to 0.33 mm (330 .mu.m) while the sub-pixel pitch is equal to 0.11 mm (110 .mu.m).
In the organic thin-film EL device due to the three-color independent luminescent system, it is possible to obtain high luminescent efficiency with a simple structure. However, the sub-pixel pitch of the pixel is equal to about 100 .mu.m or more, like the prototype of the above-mentioned two color organic thin-film EL displays.
It is necessary not only to develop a pattern mask of high accuracy, but also to develop a manufacturing method using a fine moving mechanism of a pattern mask having sufficient accuracy in order to finely separate a luminescent layer formed by excessively thin organic vaporized film into a sub-pixel of high accuracy of several tens .mu.m.